Hybrid membranes containing titanium dioxide doped with fluorine

Abstract

Hybrid membranes based on crystalline titanium dioxide containing fluorine atoms within the crystalline lattice comprising atoms of titanium and oxygen are described; these hybrid membranes are particularly suitable for the production of fuel cells and electrolyzers. A process for producing the aforesaid hybrid membranes is also described.

The invention claimed is: 
     
       1. A method of preparing ion conducting inorganic/organic hybrid membranes, comprising using fluorine-doped crystalline titanium dioxide particles to prepare ion conducting inorganic/organic hybrid membranes wherein the fluorine-doped crystalline titanium dioxide particles is in the form of crystalline titanium dioxide particles having an average particle size of between 10 and 500 nm and a having fluorine content of between 0.5 and 5% by weight. 
     
     
       2. The method of  claim 1  wherein the inorganic/organic hybrid membranes comprise proton conducting inorganic/organic hybrid membranes. 
     
     
       3. The method of  claim 1  wherein the fluorine content is between 1.0 and 4% by weight. 
     
     
       4. The method of  claim 1  wherein the crystalline titanium dioxide particles have an average particle size of between 50 and 300 nm. 
     
     
       5. The method of  claim 1  wherein the crystalline titanium dioxide particles comprise hydroxy groups, ammonium cations and nitrogen oxides. 
     
     
       6. The method of  claim 1  wherein the crystalline titanium dioxide particles have a nitrogen content of between 0.2 and 8% by weight. 
     
     
       7. The method of  claim 6  wherein the crystalline titanium dioxide particles have a nitrogen content of between 0.3 and 7.5% by weight. 
     
     
       8. The method of  claim 6  wherein the crystalline titanium dioxide particles have a nitrogen content of between 2.5 and 7% by weight. 
     
     
       9. The method of  claim 1  wherein the crystalline titanium dioxide particles have a hydrogen content of between 0.05 and 4% by weight. 
     
     
       10. The method of  claim 9  wherein the crystalline titanium dioxide particles have a hydrogen content of between 0.08 and 3% by weight. 
     
     
       11. The method of  claim 9  wherein the crystalline titanium dioxide particles have a hydrogen content of between 1.5 and 2.5% by weight. 
     
     
       12. The method of  claim 1  wherein fluorine in the fluorine-doped crystalline titanium dioxide particles is present in a surface layer of the fluorine-doped crystalline titanium dioxide particles. 
     
     
       13. The method of  claim 12  wherein at least 90% of the fluorine content is present in a surface layer of the fluorine-doped crystalline titanium dioxide particles. 
     
     
       14. The method of  claim 13  wherein the surface layer has an average thickness of between 0.6 and 10 nm. 
     
     
       15. The method of  claim 1  wherein the fluorine-doped crystalline titanium dioxide particles have hydroxy groups present in a surface layer.